The disclosure relates to apparatus and methods of testing a memory element, more specifically to the apparatus and methods of electrical characterization of a memory element organized in a cross-point configuration.
A large class of non-volatile memories contain two-terminal elements whose resistance can be changed by electrical stimulus, usually a voltage or/and current pulse (examples of such memories are Magneto resistive Random Access Memory (MRAM), Phase Change Memory (PCM), Resistive Random Access Memory (ReRAM), and other. Usually the memory elements are embedded between interconnect layers of integrated circuits, in so-called Back-End of the Line (BEOL). These memories are organized in an array, as rows (also referred to as word lines) and columns (also referred to as bit lines) and require additional circuit elements for their operation. Exemplary additional circuit elements include selectors, to turn off the memory elements which are not being read or written to at a given time. Typically, the selectors include transistors or diodes or a combination of both. In a typical semiconductor memory manufacturing process, the additional circuit elements are built on a silicon substrate which is followed by the building of the memory elements on the same substrate.
During memory technology development, process optimization, technology transfer from one manufacturing facility to another, the manufacturer needs to build test structures and memory arrays for functional tests, to determine their parametric properties, yield entitlement, and to sort the defective elements.